No start condirion/ Have spark, have gas, NO injector pulse.

[speec]

i am running out of patience with this car, i have spark, i have fuel at the rail, cranks and cranks but still won't start. i have replaced coilpack, engine speed sensor, cam sensor, ECU and a few more things. i get no pulse at the injectors, only two pulses at first but then nothing else. btw its a 96 quattro AAH engine, help is greatly appreciated

[wolfe2118]

Any codes?

[speec]

I tried several scantools and all of them says there is no trouble codes stored.

[S-lime]

Sounds like bad ground/wiring. Pull out the multi meter haha! Check for power at injectors first of all.

[speec]

The injectors have 12v all of them, and all the grounds in the ECU are ok, this is driving me crazy

[Tjtalan]

I would test for fuel pressure with a gauge. Having fuel at the rail does not always mean pressure. Once fuel and spark is confirmed its time to check pulse at the injectors.

You should get battery volts with the key on, ground is supplied by the ECU to fire each injector. The best way to check the pulse is with a noid light, you can get one cheep at Autozone.

[speec]

The fuel pressure is tested and ok, in fact the pressure regulator and the fuel pump are completely new. The spark is present too, the only thing that is missing is the injector pulse. I tested the pulse with a LED light, when I crank the engine the ECU sends two pulses (the LED blink twice) and then just stop sending the pulses. I can make a video and post it if its required.

[Tjtalan]

The fuel pressure is tested and ok, in fact the pressure regulator and the fuel pump are completely new. The spark is present too, the only thing that is missing is the injector pulse. I tested the pulse with a LED light, when I crank the engine the ECU sends two pulses (the LED blink twice) and then just stop sending the pulses. I can make a video and post it if its required.

Unfortunately if you've been over everything and it checks out, then the most likely scenario is the ECU. Again this is based off your description, if you have fuel and spark, power to the injectors, all that's missing is the ECUs ground signal. Make sure all the grounds are good, if everything checks out replace with a known good ECU.

[Tjtalan]

But I'll say again don't trust something just because it's new, I would go over everything again. Check fuel pressure with the gauge, verify spark one last time.

[speec]

I just replaced the ECU as I said and the exact same problem still there. I cannot believe that the "new" ECU have the exact same fault the old ECU has, that kind of coincidence it's almost impossible I think. I don't know what else to look for or what to do next...

[speec]

There is one thing that called my attention, and is the fact that both ECU's the old and the new send two pulses and then suddenly stop sending them, I've never seen anything like that in other cars.

I'm completely sure that the fuel pressure and the spark are both pressent and ok, i've check that several times and there is no issues in any of them.

[Tjtalan]

There is one thing that called my attention, and is the fact that both ECU's the old and the new send two pulses and then suddenly stop sending them, I've never seen anything like that in other cars.

I'm completely sure that the fuel pressure and the spark are both pressent and ok, i've check that several times and there is no issues in any of them.

I just noticed your in Venezuela, is it immobilizer equipped?

[speec]

No, this car was imported from the US, so as far i know this version it's not immo equipped. At first I thought it colud be an immo issue but there is no immo module in the car and the immo light don't turn on.

[S-lime]

Not too sure if you have already but I'd start testing/replacing fuses and relays.

[speec]

I'm testing all the relays and all the ECU wires and some internal wires and everything appears to be fine, i'm running out of ideas with this car

Here are some pics of the relays and the ECU:

[woolveren]

I'm testing all the relays and all the ECU wires and some internal wires and everything appears to be fine, i'm running out of ideas with this car

AAH uses Ignition Control Module, did you check it yet? If the ICM is bad, then the car will just turn over without starting.

Follow this link below, its for AEB engines but should be close..

https://www.youtube.com/watch?v=YYpTwRYV1_I

[speec]

I already replaced the ICM and the new one it's working fine. The car have perfect spark and fuel pressure in the rail.

[woolveren]

I already replaced the ICM and the new one it's working fine. The car have perfect spark and fuel pressure in the rail.

I know you have changed the crank and cam sensor, but to me this sounds like one of them is either not doing its job or it could be that the ecm is not actually getting the signal from one of these sensors due to a bad connection between the sensor and the ecm. If the ecu don't get the rpm info or the pulse width from cam sensor then it will stop firing the injector assuming the car has stopped running. I know you have changed ecm and the sensors, but as Tjtalan said there is no guarantee they are all working just because they are new or was replaced. Check the crank sensor resistance(should read around 500-1000 ohms when checked between pin 2 & 3)and make sure there are no shorts between its wires (between pins 1-2 and 1-3). Also check the wiring between sensors and ecm connectors and make sure everything is good and showing low resistance(1.5ohms max).

[speec]

I already bought 3 crank sensors, that was my first tought when all this issue started. The 3 crank sensors resistance read around 900 and 1100 ohms and all the wiring between the ECU and the connectors reads around 0.9 ohms, in addition to that I tested the crank sensors with a LED light to see if they are sending the signals and I noticed that if I install the sensors with the little o-ring that comes with them in the package they don't send any signal, but if I remove the o-ring and install without that they send the signal (the LED light starts to blink really fast when the engine cranks, so fast that it's almost impossible to see the blinking), so I don't know if i'm putting the crank sensor in the right spot (should be right between the gearbox and the engine as i know) or they need a special adjustment so they can send the right signal to the ECU and i'm installing them in the wrong way.

Here's a video of a test that I made with an LED light in the connector of one of the injectors to show how the ECU send two pulses and then just stop and do nothing else:

[Nollywood]

Ah. The early Hitachi ECU...

Was this car bought running? Did it suddenly cut out, or it simply failed to start once you shut it down?

I would consider a bad flywheel. The 12V engines (2.6/2.8) utilised a different ignition firing system to the 30V variants. Additionally, it uses an RPM sender, which counts the flywheel teeth (about 136 from memory). No 60-2 teeth trigger wheel here, instead it uses a firing pin, or welded on square to provide a TDC reference (pretty similar to the I5 20V 7A engines).

A bad RPM sender will shut down the motor if it fails in service, a bad TDC sender won't. It will simply fail to start once YOU shut the engine off.

It is possible the TDC firing pin on the flywheel is broken, or otherwise damaged. If this is the case, this is about the only time a push start will fire up an engine that cranks with the ignition key. Try this first.

Another culprit could be a bad ignition switch, or ECM relay. But I suspect your issues are flywheel-related, (mechanical) which would explain the absense of DTC's stored in the ECM.

[woolveren]

if I remove the o-ring and install without that they send the signal (the LED light starts to blink really fast when the engine cranks, so fast that it's almost impossible to see the blinking)

LED shouldn't be flashing that fast when connected to the crank sensor, below is a VR6 video which I have bookmarked sometime in the past so you can compare the led blinking with yours.

https://www.youtube.com/watch?v=BtkENa-JYmA

As Nollywood said,check the flywheel and make sure the timing pin is there. It should be visible through the hole where the crank position sensor is located when the sensor is removed, and you can then slowly turn the crankshaft to determine if the pin is still there or not.

[speec]

All the flywheel explanation makes perfect sense, I think that could really be the problem in this car. I bought the car not running, the previous owner told me that the car one day suddenly stops, but I don't believe that story. So the next step it's pretty clear to me now, i'm going to check the flywheel in the upcoming days and will let you guys know if that finally is the problem.

PS: if I swap the ECU the new one needs to be programmed or something like that?

Thanks so much to everyone, this has been really helpful!!

[woolveren]

So the next step it's pretty clear to me now, i'm going to check the flywheel in the upcoming days and will let you guys know if that finally is the problem.

Should be close.. https://www.youtube.com/watch?v=EwJBl_W0eYc

if I swap the ECU the new one needs to be programmed or something like that?

http://www.audiforums.com/forum/diy-...ur-car-181068/

[speec]

Great info woolveren! That will be really helpful.

I dind't recode the new ECU, it has the exact same part number (8D0 906 266B and MMS-411A) than the old one. In order to do the recode I need to buy a VAG-COM scantool, I have been looking on amazon and noticed that there are too many versions at different price range, is there any specific one or anything that i should have in mind when buying one?

Once again thanks!!